Magnetocaloric Properties of A-Site-Doped La 2 NiMnO 6 for Environmentally Friendly Refrigeration
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https://doi.org/10.1007/s11664-020-08477-0 2020 The Minerals, Metals & Materials Society
ASIAN CONSORTIUM ACCMS–INTERNATIONAL CONFERENCE ICMG 2020
Magnetocaloric Properties of A-Site-Doped La2NiMnO6 for Environmentally Friendly Refrigeration E. MEHER ABHINAV,1 D. JAISON,1 ANURAJ SUNDARARAJ,1 GOPALAKRISHNAN CHANDRASEKARAN ,2,4 and S.V. KASMIR RAJA3 1.—Nanotechnology Research Centre, SRM Institute of Science and Technology, Chennai, Tamil Nadu 603203, India. 2.—Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Chennai, Tamil Nadu 603203, India. 3.—Directorate of Research, SRM Institute of Science and Technology, Chennai, Tamil Nadu 603203, India. 4.—e-mail: [email protected]
La2NiMnO6 double perovskite material that simultaneously exhibits both electric and magnetic ordering is used in energy-efficient electronic applications due to its lower power dissipation. The magnetic and electric ordering of Ni and Mn depend on the site occupancy and exchange mechanism driven by the anions, making La2NiMnO6 a widely explored material for such studies. The magnetocaloric properties of A-site-doped (Sr2+, Gd3+) double perovskite La2NiMnO6 have been investigated experimentally. The synthesized samples showed Pbnm orthorhombic symmetry with P21/n configuration. The Curie temperature (TC) of La2NiMnO6 (LMN) increased from 277 K to 284 K upon Gd doping due to strong exchange interactions and long-range ordering of Ni2+/Mn4+. Meanwhile, the Tc of LMN was observed to be 268 K upon Sr2+ doping, suggesting the possibility of antiferromagnetic ordering. Sr2+-doped (hole-doped) LMN showed lower Tc, magnetic entropy, and relative cooling power (RCP), which may be due to the increase in antisite disorder and exchange bias effect. The chemical stability, tunable transition temperature around room temperature with good control over entropy, wider operating temperature range, and high RCP at lower applied magnetic field make LMN and A-site-doped LMN potential refrigerant materials for use in energy-efficient room-temperature magnetic cooling systems. Key words: Double perovskite, solid-state refrigeration, entropy change, La2NiMnO6 (LMN), magnetic refrigeration
INTRODUCTION Refrigeration is a major energy-demanding process in the world, and conventional methods for refrigeration pose a great threat to the environment. Consequently, finding solid-state refrigerant systems with higher efficiency that can prevent the use of ozone-depleting gases such as chlorofluorocarbons (CFCs) and hydroclorofluorocarbons (HCFCs) has become critically important.
(Received March 13, 2020; accepted September 9, 2020)
Magnetocaloric cooling systems have attract interest from researchers, particularly for use in roomtemperature cooling systems and cryogenics for gas liquefaction. In 1917, Weiss and Piccard discovered the caloric effect for the first time.1 Giauque and Debye explained how the magnetocaloric effect (MCE) can be used to achieve temperatures in the cryogenic range, and Giauque was awarded the Nobel Prize in 1949
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